Use of Baffles in Open Channel Expansion

Laboratory tests were conducted to determine the efficacy of using baffle piers in an open-channel outlet transition with flow at sub-critical velocity throughout. It was found that the use of such baffles will substantially reduce the structure length required to achieve a given velocity reduction. A triangular three-baffle arrangement will permit flow expansion, without separation, in a straight walled transition with a side-wall flare as rapid as 1 in 4. The head loss in such an outlet is approximately 0.8 times the theoretical Borda head loss for an abrupt expansion. Possible useful applications of the principle include diverging transitions for flumes, siphons, and culverts.